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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/ipc/namespace.c
4 * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
5 */
6
7#include <linux/ipc.h>
8#include <linux/msg.h>
9#include <linux/ipc_namespace.h>
10#include <linux/rcupdate.h>
11#include <linux/nsproxy.h>
12#include <linux/slab.h>
13#include <linux/cred.h>
14#include <linux/fs.h>
15#include <linux/mount.h>
16#include <linux/user_namespace.h>
17#include <linux/proc_ns.h>
18#include <linux/sched/task.h>
19
20#include "util.h"
21
22static struct ucounts *inc_ipc_namespaces(struct user_namespace *ns)
23{
24 return inc_ucount(ns, current_euid(), UCOUNT_IPC_NAMESPACES);
25}
26
27static void dec_ipc_namespaces(struct ucounts *ucounts)
28{
29 dec_ucount(ucounts, UCOUNT_IPC_NAMESPACES);
30}
31
32static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
33 struct ipc_namespace *old_ns)
34{
35 struct ipc_namespace *ns;
36 struct ucounts *ucounts;
37 int err;
38
39 err = -ENOSPC;
40 ucounts = inc_ipc_namespaces(user_ns);
41 if (!ucounts)
42 goto fail;
43
44 err = -ENOMEM;
45 ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
46 if (ns == NULL)
47 goto fail_dec;
48
49 err = ns_alloc_inum(&ns->ns);
50 if (err)
51 goto fail_free;
52 ns->ns.ops = &ipcns_operations;
53
54 refcount_set(&ns->count, 1);
55 ns->user_ns = get_user_ns(user_ns);
56 ns->ucounts = ucounts;
57
58 err = sem_init_ns(ns);
59 if (err)
60 goto fail_put;
61 err = msg_init_ns(ns);
62 if (err)
63 goto fail_destroy_sem;
64 err = shm_init_ns(ns);
65 if (err)
66 goto fail_destroy_msg;
67
68 err = mq_init_ns(ns);
69 if (err)
70 goto fail_destroy_shm;
71
72 return ns;
73
74fail_destroy_shm:
75 shm_exit_ns(ns);
76fail_destroy_msg:
77 msg_exit_ns(ns);
78fail_destroy_sem:
79 sem_exit_ns(ns);
80fail_put:
81 put_user_ns(ns->user_ns);
82 ns_free_inum(&ns->ns);
83fail_free:
84 kfree(ns);
85fail_dec:
86 dec_ipc_namespaces(ucounts);
87fail:
88 return ERR_PTR(err);
89}
90
91struct ipc_namespace *copy_ipcs(unsigned long flags,
92 struct user_namespace *user_ns, struct ipc_namespace *ns)
93{
94 if (!(flags & CLONE_NEWIPC))
95 return get_ipc_ns(ns);
96 return create_ipc_ns(user_ns, ns);
97}
98
99/*
100 * free_ipcs - free all ipcs of one type
101 * @ns: the namespace to remove the ipcs from
102 * @ids: the table of ipcs to free
103 * @free: the function called to free each individual ipc
104 *
105 * Called for each kind of ipc when an ipc_namespace exits.
106 */
107void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
108 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
109{
110 struct kern_ipc_perm *perm;
111 int next_id;
112 int total, in_use;
113
114 down_write(&ids->rwsem);
115
116 in_use = ids->in_use;
117
118 for (total = 0, next_id = 0; total < in_use; next_id++) {
119 perm = idr_find(&ids->ipcs_idr, next_id);
120 if (perm == NULL)
121 continue;
122 rcu_read_lock();
123 ipc_lock_object(perm);
124 free(ns, perm);
125 total++;
126 }
127 up_write(&ids->rwsem);
128}
129
130static void free_ipc_ns(struct ipc_namespace *ns)
131{
132 sem_exit_ns(ns);
133 msg_exit_ns(ns);
134 shm_exit_ns(ns);
135
136 dec_ipc_namespaces(ns->ucounts);
137 put_user_ns(ns->user_ns);
138 ns_free_inum(&ns->ns);
139 kfree(ns);
140}
141
142/*
143 * put_ipc_ns - drop a reference to an ipc namespace.
144 * @ns: the namespace to put
145 *
146 * If this is the last task in the namespace exiting, and
147 * it is dropping the refcount to 0, then it can race with
148 * a task in another ipc namespace but in a mounts namespace
149 * which has this ipcns's mqueuefs mounted, doing some action
150 * with one of the mqueuefs files. That can raise the refcount.
151 * So dropping the refcount, and raising the refcount when
152 * accessing it through the VFS, are protected with mq_lock.
153 *
154 * (Clearly, a task raising the refcount on its own ipc_ns
155 * needn't take mq_lock since it can't race with the last task
156 * in the ipcns exiting).
157 */
158void put_ipc_ns(struct ipc_namespace *ns)
159{
160 if (refcount_dec_and_lock(&ns->count, &mq_lock)) {
161 mq_clear_sbinfo(ns);
162 spin_unlock(&mq_lock);
163 mq_put_mnt(ns);
164 free_ipc_ns(ns);
165 }
166}
167
168static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
169{
170 return container_of(ns, struct ipc_namespace, ns);
171}
172
173static struct ns_common *ipcns_get(struct task_struct *task)
174{
175 struct ipc_namespace *ns = NULL;
176 struct nsproxy *nsproxy;
177
178 task_lock(task);
179 nsproxy = task->nsproxy;
180 if (nsproxy)
181 ns = get_ipc_ns(nsproxy->ipc_ns);
182 task_unlock(task);
183
184 return ns ? &ns->ns : NULL;
185}
186
187static void ipcns_put(struct ns_common *ns)
188{
189 return put_ipc_ns(to_ipc_ns(ns));
190}
191
192static int ipcns_install(struct nsproxy *nsproxy, struct ns_common *new)
193{
194 struct ipc_namespace *ns = to_ipc_ns(new);
195 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
196 !ns_capable(current_user_ns(), CAP_SYS_ADMIN))
197 return -EPERM;
198
199 /* Ditch state from the old ipc namespace */
200 exit_sem(current);
201 put_ipc_ns(nsproxy->ipc_ns);
202 nsproxy->ipc_ns = get_ipc_ns(ns);
203 return 0;
204}
205
206static struct user_namespace *ipcns_owner(struct ns_common *ns)
207{
208 return to_ipc_ns(ns)->user_ns;
209}
210
211const struct proc_ns_operations ipcns_operations = {
212 .name = "ipc",
213 .type = CLONE_NEWIPC,
214 .get = ipcns_get,
215 .put = ipcns_put,
216 .install = ipcns_install,
217 .owner = ipcns_owner,
218};
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/ipc/namespace.c
4 * Copyright (C) 2006 Pavel Emelyanov <xemul@openvz.org> OpenVZ, SWsoft Inc.
5 */
6
7#include <linux/ipc.h>
8#include <linux/msg.h>
9#include <linux/ipc_namespace.h>
10#include <linux/rcupdate.h>
11#include <linux/nsproxy.h>
12#include <linux/slab.h>
13#include <linux/cred.h>
14#include <linux/fs.h>
15#include <linux/mount.h>
16#include <linux/user_namespace.h>
17#include <linux/proc_ns.h>
18#include <linux/sched/task.h>
19
20#include "util.h"
21
22/*
23 * The work queue is used to avoid the cost of synchronize_rcu in kern_unmount.
24 */
25static void free_ipc(struct work_struct *unused);
26static DECLARE_WORK(free_ipc_work, free_ipc);
27
28static struct ucounts *inc_ipc_namespaces(struct user_namespace *ns)
29{
30 return inc_ucount(ns, current_euid(), UCOUNT_IPC_NAMESPACES);
31}
32
33static void dec_ipc_namespaces(struct ucounts *ucounts)
34{
35 dec_ucount(ucounts, UCOUNT_IPC_NAMESPACES);
36}
37
38static struct ipc_namespace *create_ipc_ns(struct user_namespace *user_ns,
39 struct ipc_namespace *old_ns)
40{
41 struct ipc_namespace *ns;
42 struct ucounts *ucounts;
43 int err;
44
45 err = -ENOSPC;
46 again:
47 ucounts = inc_ipc_namespaces(user_ns);
48 if (!ucounts) {
49 /*
50 * IPC namespaces are freed asynchronously, by free_ipc_work.
51 * If frees were pending, flush_work will wait, and
52 * return true. Fail the allocation if no frees are pending.
53 */
54 if (flush_work(&free_ipc_work))
55 goto again;
56 goto fail;
57 }
58
59 err = -ENOMEM;
60 ns = kzalloc(sizeof(struct ipc_namespace), GFP_KERNEL_ACCOUNT);
61 if (ns == NULL)
62 goto fail_dec;
63
64 err = ns_alloc_inum(&ns->ns);
65 if (err)
66 goto fail_free;
67 ns->ns.ops = &ipcns_operations;
68
69 refcount_set(&ns->ns.count, 1);
70 ns->user_ns = get_user_ns(user_ns);
71 ns->ucounts = ucounts;
72
73 err = mq_init_ns(ns);
74 if (err)
75 goto fail_put;
76
77 err = -ENOMEM;
78 if (!setup_mq_sysctls(ns))
79 goto fail_put;
80
81 if (!setup_ipc_sysctls(ns))
82 goto fail_mq;
83
84 err = msg_init_ns(ns);
85 if (err)
86 goto fail_ipc;
87
88 sem_init_ns(ns);
89 shm_init_ns(ns);
90
91 return ns;
92
93fail_ipc:
94 retire_ipc_sysctls(ns);
95fail_mq:
96 retire_mq_sysctls(ns);
97
98fail_put:
99 put_user_ns(ns->user_ns);
100 ns_free_inum(&ns->ns);
101fail_free:
102 kfree(ns);
103fail_dec:
104 dec_ipc_namespaces(ucounts);
105fail:
106 return ERR_PTR(err);
107}
108
109struct ipc_namespace *copy_ipcs(unsigned long flags,
110 struct user_namespace *user_ns, struct ipc_namespace *ns)
111{
112 if (!(flags & CLONE_NEWIPC))
113 return get_ipc_ns(ns);
114 return create_ipc_ns(user_ns, ns);
115}
116
117/*
118 * free_ipcs - free all ipcs of one type
119 * @ns: the namespace to remove the ipcs from
120 * @ids: the table of ipcs to free
121 * @free: the function called to free each individual ipc
122 *
123 * Called for each kind of ipc when an ipc_namespace exits.
124 */
125void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
126 void (*free)(struct ipc_namespace *, struct kern_ipc_perm *))
127{
128 struct kern_ipc_perm *perm;
129 int next_id;
130 int total, in_use;
131
132 down_write(&ids->rwsem);
133
134 in_use = ids->in_use;
135
136 for (total = 0, next_id = 0; total < in_use; next_id++) {
137 perm = idr_find(&ids->ipcs_idr, next_id);
138 if (perm == NULL)
139 continue;
140 rcu_read_lock();
141 ipc_lock_object(perm);
142 free(ns, perm);
143 total++;
144 }
145 up_write(&ids->rwsem);
146}
147
148static void free_ipc_ns(struct ipc_namespace *ns)
149{
150 /*
151 * Caller needs to wait for an RCU grace period to have passed
152 * after making the mount point inaccessible to new accesses.
153 */
154 mntput(ns->mq_mnt);
155 sem_exit_ns(ns);
156 msg_exit_ns(ns);
157 shm_exit_ns(ns);
158
159 retire_mq_sysctls(ns);
160 retire_ipc_sysctls(ns);
161
162 dec_ipc_namespaces(ns->ucounts);
163 put_user_ns(ns->user_ns);
164 ns_free_inum(&ns->ns);
165 kfree(ns);
166}
167
168static LLIST_HEAD(free_ipc_list);
169static void free_ipc(struct work_struct *unused)
170{
171 struct llist_node *node = llist_del_all(&free_ipc_list);
172 struct ipc_namespace *n, *t;
173
174 llist_for_each_entry_safe(n, t, node, mnt_llist)
175 mnt_make_shortterm(n->mq_mnt);
176
177 /* Wait for any last users to have gone away. */
178 synchronize_rcu();
179
180 llist_for_each_entry_safe(n, t, node, mnt_llist)
181 free_ipc_ns(n);
182}
183
184/*
185 * put_ipc_ns - drop a reference to an ipc namespace.
186 * @ns: the namespace to put
187 *
188 * If this is the last task in the namespace exiting, and
189 * it is dropping the refcount to 0, then it can race with
190 * a task in another ipc namespace but in a mounts namespace
191 * which has this ipcns's mqueuefs mounted, doing some action
192 * with one of the mqueuefs files. That can raise the refcount.
193 * So dropping the refcount, and raising the refcount when
194 * accessing it through the VFS, are protected with mq_lock.
195 *
196 * (Clearly, a task raising the refcount on its own ipc_ns
197 * needn't take mq_lock since it can't race with the last task
198 * in the ipcns exiting).
199 */
200void put_ipc_ns(struct ipc_namespace *ns)
201{
202 if (refcount_dec_and_lock(&ns->ns.count, &mq_lock)) {
203 mq_clear_sbinfo(ns);
204 spin_unlock(&mq_lock);
205
206 if (llist_add(&ns->mnt_llist, &free_ipc_list))
207 schedule_work(&free_ipc_work);
208 }
209}
210
211static inline struct ipc_namespace *to_ipc_ns(struct ns_common *ns)
212{
213 return container_of(ns, struct ipc_namespace, ns);
214}
215
216static struct ns_common *ipcns_get(struct task_struct *task)
217{
218 struct ipc_namespace *ns = NULL;
219 struct nsproxy *nsproxy;
220
221 task_lock(task);
222 nsproxy = task->nsproxy;
223 if (nsproxy)
224 ns = get_ipc_ns(nsproxy->ipc_ns);
225 task_unlock(task);
226
227 return ns ? &ns->ns : NULL;
228}
229
230static void ipcns_put(struct ns_common *ns)
231{
232 return put_ipc_ns(to_ipc_ns(ns));
233}
234
235static int ipcns_install(struct nsset *nsset, struct ns_common *new)
236{
237 struct nsproxy *nsproxy = nsset->nsproxy;
238 struct ipc_namespace *ns = to_ipc_ns(new);
239 if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN) ||
240 !ns_capable(nsset->cred->user_ns, CAP_SYS_ADMIN))
241 return -EPERM;
242
243 put_ipc_ns(nsproxy->ipc_ns);
244 nsproxy->ipc_ns = get_ipc_ns(ns);
245 return 0;
246}
247
248static struct user_namespace *ipcns_owner(struct ns_common *ns)
249{
250 return to_ipc_ns(ns)->user_ns;
251}
252
253const struct proc_ns_operations ipcns_operations = {
254 .name = "ipc",
255 .type = CLONE_NEWIPC,
256 .get = ipcns_get,
257 .put = ipcns_put,
258 .install = ipcns_install,
259 .owner = ipcns_owner,
260};